The Passover Week remembered God’s protection and deliverance of his people from Egypt. It reminded Israel that God had passed over the blood-covered Israelite homes while killing the firstborn of Egypt who were not covered by the blood of a substitute sacrifice. Through this act of judgement God worked Israel's salvation from bondage in Egypt and led them into freedom as his people.
But God didn’t just get his people out of captivity, he eventually led them into a land flowing with milk and honey. So God established the Feast of Weeks (Pentecost) to be observed 50 days after Passover as a way of celebrating that God doesn’t just rescue his people and then leave them to themselves, God ongoingly provides. His salvation is from beginning to end. He is Jehovah Jireh, "God, Our Provider". In the book of Leviticus, God instructed Israel:
“You shall count fifty days to the day after the seventh Sabbath. Then you shall present a grain offering of new grain to the LORD. You shall bring from your dwelling places two loaves of bread to be waved, made of two tenths of an ephah. They shall be of fine flour, and they shall be baked with leaven, as firstfruits to the LORD...You shall hold a holy convocation. You shall not do any ordinary work. It is a statute forever in all your dwelling places throughout your generations." (Leviticus 23:16-21)
So every year, seven weeks after Passover, Jews from all over Israel would trek to Jerusalem, bringing a portion of their grain harvest to God to offer thanks for his provision and faithfulness. It was during this festival that God chose to pour out his Spirit on Jesus' disciples, which is why, as Christians, we celebrate Pentecost. It was fitting that the promise of the Holy Spirit came during a festival focused on God's provision. God has indeed provided in the greatest way imaginable: through the person and work of Jesus, He sent his Spirit to us, to reside in us, that we might know him and live for him.
What is the Significance of the Spirit?
I will sprinkle clean water on you, and you shall be clean from all your uncleannesses, and from all your idols I will cleanse you. And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh. And I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules. (Ezekiel 36:25-27)
Throughout the Old Testament, there was an ongoing issue among God's people. Despite the fact that Israel had God's Law given to them, they couldn't keep it. Over and over again, they kept wandering from God's ways and living in sin and idolatry. The prophets rooted this conundrum in the heart. Jeremiah said, "The heart is deceitful above all things, and desperately sick." (Jeremiah 17:9). Israel's sin-sickness kept them from knowing the Lord intimately, or living for God effectively.
The nation of Israel's sinfulness limited its interaction with the Lord. God's presence was mediated primarily through the tabernacle/temple, and his Spirit would empower only the nation's leader. The average Israelite only knew God in a limited fashion. But the prophet Ezekiel pointed toward a coming day when Israel's problem would be addressed and amended. He spoke of a coming day when God would give them a new heart, and place a new spirit within them. This spirit would be God's very own Spirit, residing in them, causing them to obey Him and walk in his ways. Jeremiah said that as a result, every single member of God's covenant family would know him intimately (Jeremiah 31:34). When the Spirit was poured out at Pentecost, the prophets' hope of a new and better day was realized.
The coming of the Spirit means that we can know God in a personal way
But, as it is written,
“What no eye has seen, nor ear heard,
nor the heart of man imagined,
what God has prepared for those who love him”—
these things God has revealed to us through the Spirit. For the Spirit searches everything, even the depths of God. For who knows a person's thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God. Now we have received not the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God. And we impart this in words not taught by human wisdom but taught by the Spirit, interpreting spiritual truths to those who are spiritual.
The natural person does not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned. The spiritual person judges all things, but is himself to be judged by no one. “For who has understood the mind of the Lord so as to instruct him?” But we have the mind of Christ. (1 Corinthians 2:9-16)
Being filled with God’s Spirit means that we can know more God deeply and intimately. Through the Holy Spirit we are given the mind of Christ to know and understand God. In John 16, Jesus tells his disciples that the Spirit is given to teach and guide them into the truth.
When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. He will glorify me, for he will take what is mine and declare it to you. (John 16:13-14)